Security vendor Malwarebytes has crippled thousands of computers around the world after a faulty update was applied to its software. The faulty security update applied to the software marked legitimate system files as malware code.

"Within eight minutes, the update was pulled from our servers. Immediately thereafter, users flocked to our support helpdesk and forums to ask us for a fix."

The specific operating system files that the malware update targeted included Windows.dll and.exe files. By targeting those files, the security application prevented them from running, taking IT systems and individual computers off-line.

One company that uses a software claims that the update knocked 80% of its servers off-line. Malwarebytes maintains that it has begun reworking its update policy to ensure the sort of mistake never happens again.

"We acted over-zealously in that mission and realise far superior procedures around updating are needed. More was expected of us, and we failed," wrote Kleczynski.

"We are commissioning several new resources to stop this from happening again. We are building more redundancy to check our researchers' work and improving our peer review."

Good advice. The problem here was that users were not even running scans, yet DLLs and EXEs were getting hosed. At my office, we have the Enterprise Edition with real-time protection, and the affected PCs appeared to be compromised by malware, when it was in fact MBAM. Applications would freeze or were unable to launch. The main security suite was inoperable. So naturally, I tried to scan with MBAM and lo and behold, 2000+ "infected" files on one PC, all with the same Trojan. WTF? So I took a closer look and saw all the system files and even MBAM core files. Obviously something was fishy, so, I canceled out, hit up the web and found the support threads showing the problem. But in a way, it was a self-fulfilling prophecy. In our case at least, the program broke the system in a manner that just screamed "malware", so I can see how people could ran headfirst into more trouble, and blindly trust that the anti-malware software knew what it was doing.

Luckily, the company's fix tool worked on most users (those who couldn't even run System Restore) and de-quarantined the affected files, but some required repair installs of Windows. No idea if we'll bother renewing our licenses next year. Kinda sad, considering it's been so good thus far.